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RE: TC coil experements 7 years ago



Original poster: "Lau, Gary" <Gary.Lau@xxxxxx>

Yes!  While Gary Weaver's experiment does on the surface seem like a
definitive result, a more useful experiment would be to compare the
performance of two secondary coils with identical inductance but
different H/D ratios.

For instance, compare coil #1 - 4"x20.5" #24 H/D=5.13  L=15.84uH, to
New coil #4 - 6"x10.5" #24 H/D=1.75 L=15.80uH

Care would also have to be taken to keep the pri/sec coupling identical.
This would keep everything but the H/D ratio constant.  If the power
level was kept small enough that secondary flashover and racing sparks
don't occur on the shorter coil, I would wager that no difference in
performance would be seen.

Regards, Gary Lau
MA, USA

> Original poster: Finn Hammer <f-h@xxxx>
>
> Gary,
>
> Secondary inductance went from 9,96mH trough 21,54mH to 36,87mH
> Your resonant frequency went from 289kHz trough 197,42kHz to
146,94kHz
> Your primary inductance went from 28,5uH trough 65,3uH to 117,6uH
>
> This means that your surge impedance went from:
> 53,38 ohms trough 80,8 ohms to 108,4 ohms
> and your primary peak current (assuming 15000 volts on cap) went from
> 280A trough 185,6A to 138,3 A
>
> What I am saying:
>
> You did not take gap losses into consideration, and they might have
> been the cause of the difference in performance.
>
> Cheers, Finn Hammer
>
>
> Tesla list skrev:
> >Original poster: gary350@xxxxxxxxxxxxx
> >Vanderbelt University did some research on Tesla Coils.  The best
> >length to diameter ratio is 3 to 1 according to them.  Research
> >shows 3/1 is better than 4/1 and that is better than 5/1.  If you
> >are going for absolute maximum output try 3/1 ratio.
> >I did some experenents with this myself and built 3 Tesla
> >Coils.  The 3 TCs are identical only thing that changes is the
> >secondary coil diameter to length ratio.
> >TC #1, 950 turns #24 wire 20.5 inches in length wound on 4" PVC pipe.
> >TC #2, 950 turns #24 wire 20.5 inches in length wound on 6" PVC pipe.
> >TC #3, 950 turns #24 wire 20.5 inches in length wound on 8" PVC pipe.
> >I used the same 15K 60ma neon sign transformer.
> >I used the same .01 uf capacitor.
> >I used the same VSVFSG spark gap.
> >I used the same top load, toroid 14" diameter 4.5" thick.
> >I built a flat would primary coil for each secondary coil.  The
> >inside turn of each primary was 2" from the secondary coil.  Primary
> >were all would with 1/4" copper tubing, flat wound, spacing 1/2"
> >center to center, 18 turns each.
> >The only thing in the circuit that changed was the secondary
> >coil.  The primary coil physical shape had to accommodate the
secondary coil.
>
>
>